With your cryptic reference to fuel filters and sight glasses on a LFO setup makes one think that what was causing issue was a defect with the fuel supply/return system. It has been my experience, all though limited on ultra modern electronically controlled engines, that many types of modern engines circulate/recirculate much higher volumes of fuel through the system than is consumed. If this circulated/recirculated fuel flow is some how restricted possibly by improper design of the return side or a failed back pressure regulator or for some other reason, the fuel being recirculated could overheat and cause a loss of fuel viscosity or cause the system to vapour lock. Where on LFO engines,the fuel temperature at the rail may not necessarily be monitored would make a high fuel rail temperature difficult to detect.

I've run across this problem before on a couple of occasions. In one case it was on a 3500 series Caterpillar and involved a complete redesign of the fuel return system to correct the problem. The other time was on a fire truck with a Detroit Engine when after running the pump for a long time in the summer after the truck's fuel tanks became overheated. Both of these engines are fitted with unit injectors (Fuel Pump & Injector nozzle in one unit) and if the fuel temperature gets too high the engine booster pump pressure and will drop off due to a lower viscosity and possible vapour locks

So could part XYZ1234 be either a missing Fuel Rail Temperature sensor which would normally have been fitted on an HFO engine, some sort of fuel temperature regulator to exchange recirculated fuel and or increase fuel flow, or a fuel cooler?

Think maybe we are talking cross references here Dave.My fuel filtration reference was purely a " thought filtration " only and compared to a real life fuel system which we are all familiar with and understand.I was drawing parallels to a familiar set up and was trying to portray the fact that you have cracked the problem in your earlier write ups but as you stated a few possibilities you have to separate the correct answer and as CR diagnostics is an Elimination process the right from the wrong has to be separated.In other words Eliminated.My " thought process " of elimination is perhaps akin to " filtering " your answers and drawing comparisons to a fuel filtration system .In other words get all your replies together, filter out the incorrect replies leaving only the correct one.So your filtration has to be not by picturing the set up but by filtering in your brain what you have already said on the site.The picture in the mind of all your ideas churning around in a sight glass and bleeding out the answers

Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Sorry it went too quickSo the bleeding out of the answers is just a comparison to a real life fuel system.So cobble up a filtering system in your head, forget all about HEUI systems and the like.So to revert to my equation viz,DWS Answers/ Elimination = Diagnostic AnswerSorry you didn't understand all my ramblings but the fuel system reference was for illustrative purposes only.Don't give up, you are nearly there.JK has complained before about my questions and I am beginning to wonder if perhaps there is a different " take " on subjects over there versus here, any one over there got any experience on this I wonder?In conclusion basically which of your remarks is the right answer?

Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Between we covered various ways of smoothing the power supply with Capacitors across the supply and Diodes across the inductive loads, although everybody omitted an Inductance as a way of smoothing the power supply.

Could it be as simple as screwing in a diode in to a torque setting similar to the Rotating Diodes on Alternators, and using it to smooth the Voltage spikes??

BP

It is always better to ask a stupid question than to do a stupid thing.

Sorry BP, back to the drawing board on this one.Further clues?Part no XYZ1234, the documentation supplied with this modification kit clearly states that unless after fitting it the part removed to fit the part XYZ1234 is torqued to about ( from memory ) approx 24 foot pounds there is no warranty whatsoever that the problem will be solved.This sounded weird to me back then but when all is revealed you will understand why the correct torque is essential.It's certainly different from anything else I had ever encountered at that time.Difficult one unless you have had it happen to you.Keep filtering, the info posted on this one on site needs straining / filtering / eliminating as the answer has already been stated correctly.But where? You

Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Would it be that the insulator in a suspect sensor had been over stressed and cracked, possibly due to over torquing on initial installation, expansion and contraction due to heating & cooling or vibration, resulting in an intermittent sensor fault? Hence a specific torque specification on the replacement.

Sorry Dave / BP, this particular problem does not involve the replacement of any components whatsoever, the part requiring attention is removed, XYZ1234 is "fitted" in accordance with the manufactures requirements and the original removed component refitted.Interestingly to note when this part was originally fitted by the makers no torque settings were applied whatsoever but in order to fulfill the manufactures instructions concerning the " modification kit " it is essential to conform with the schematic diagram supplied concerning equals and opposites torqueing sequences and settings.Plus of course starting going round the 10/12 bolts torquewise stagewise starting at 10 foot pounds and working up to the lower twenties foot pounds.After a year plus of being unable to crack this one ( by anyone including the makers ) it amazingly solved the problem.Although this was one of the first major introductions to very different defects compared to the my past re mechanical systems etc this new fangled CR I and others thought part no XYZ1234 was a p sstake but like the iced water poured over the top gallery of the seized in line injection pump breakdown ( the sulphur reduction problem re lubing the pump and rack bar ) I was yet again proven to be wrong.And so the apprenticeship continues.

Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

Although DW has told us what the problem is here his filtration plant in his head has not yet to date managed to perform the CR Golden rule " process of elimination " in order to crack this one and separate the correct answers from the incorrect ones.Upping the microns in the filtration plant in his head not being forthcoming here is a photo of part A of the specialist modification kit supplied.The kit is in three identical parts together with the workshop " manual " enabling us to fit the part correctly and stage torque after refitting the offending part.

Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

So the long awaited " special modification kit " eventually arrives, eager hands break open the sealed packages desperate to know what on earth can it be. ( that's your clue, earth )Out falls three toothpaste type tubes complete with an instruction manual on how to fitOn the tubes it stated " special silicon grease " and to be applied in occordance with the makers instructions only.What the hell?What's this, another windup?This Common Rail things another joke comment all hands.The instructions would have been probably written by a lawyer rather than a marine engineer." extensive ongoing laboratory tests have revealed that in extreme conditions there could be an induced failure causing ECU 'S to go down onto Limpo mode or in some cases a complete shutdown mode may occur"However should modification kit XYZ1234 be applied correctly and torqued correctly this should ensure that this will never happen and as such part of our on going commitment to our installations there is, as a gesture of goodwill no charge for the kit.Bunk.Probably hundreds of hours have been lost on not only down to Limpo but complete shutdowns have occurred .We have lost a lot of hours/ days diagnostic time as we ( together with the manufactures ) have spent a lot of time unable to correctly diagnose the fault.No admission of guilt whatsoever displayed here at all, just the helpful hand syndrome bullshit.So as per the " it's only in case of " instruction book it's remove the ECU from its backing plate and turn it over.Back then ( mid eighties ) two types of ECU 's , the self destruct one and the unbolt to split it one or the one whereby all components sealed in a resin filled box.We called it the self destruct one on account of the fact the only way to get in it was to destruct it.Looking at the back end where the ECU had been resin filled you noted that you could see the halfround sections of the resistors, diodes and the capacitators projecting up which although they were resin coated only had a thin smear over the top of the halfround sections.Now this is where the fault lay, the ECU was tracking to earth intermittently on odd occasions/ temps earthing through onto the backplate to which it was mounted.You should be aware, as we noted that this installation was NOT an insulated return system but an earthed set up as the whole engine/alternator / battery box was contained in a large lifting frame onto which the earth return battery cable was bolted.Thus by bolting any earth return wire to the frame would provide an instant earthed return to the battery without running a separate feedback.So it was apparent as to how this set up allowed the ECU to track through the back of the casing straight to earth and a complete shutdown happening.So off with the tubes caps, squirt the contents into the back casing of the ECU until it projected over the casing height taking care no air-holes anywhere.Bit like low tide really.Although no explanation was forecoming we deducted that by two stage torqueing the ECU to the backplate that an even " spew out " of the special silicon grease " ensured a blanking / insulated condition now existed between The ECU and earth.Two stage torqueing the ECU bolts using a wrist watch torque wrench the job was left overnight to " cure."

Amazingly this really worked and no more problems ensued.Several months later we had to fit new ECU 'S and send the original ones back, the new ones were resin filled flush with the casings sides, in other words high tide prevailed here all right.Talk about live and learn!All this was approx. 1985/6 and I have to say with me it never happened again re ECU tracking.So just when you think you are getting a handle on it all along comes something like this and you realise you still have a long way to go and that five year apprenticeship is still running all those years later.Think on this occasion Mr Siemens was the culprit.Like I said , unless this has happened to you personally very difficult one to crack, as Mr Siemens probably thought at the time but of course never admitted.

,

Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.